This invention relates to asphaltic compositions which are suitable for use as road paving materials.
Asphalt is a natural constituent of crude oils and is typically produced from the distillation residues of refining feedstocks. This product is of very significant industrial importance since it is widely used in the construction of roads, building materials and other industrial applications. This asphalt has normally been obtained from conventional petroleum oils.
With the changing economics of the petroleum industry, there is a trend toward the conversion of heavy hydrocarbon oils, such as distillation residues, to light and intermediate naphthas of good quality for reforming feedstocks, fuel oil and gas oils.
Most petroleum refineries have visbreaker units and produce visbreaking pitches, i.e. residues of distillation boiling above 524.degree. C. It has been reported by Giavarini, Fuel, 63, 1515 (1984) that visbreaking residuum by itself is not suitable for road asphalt production as this residuum is very temperature susceptible and is thermally unstable. Nevertheless, this visbreaking residuum would be an attractive component of a road asphalt composition if its deficiencies could be overcome.
Asphalt cement specifications for road paving purposes are given in Table 1 below.
TABLE 1 __________________________________________________________________________ Asphalt cement specifications for road purpose (16-GP-3M) Grade 85-100 120-150 150-200 ASTM Requirements Min. Max. Min. Max. Min. Max. Method __________________________________________________________________________ Penetration 85 100 120 150 150 200 D 5 (25.degree. C., 100 g, 5s) Flash point 230 -- 220 -- 220 -- D 92 (CO C, .degree.C.) Ductility 100 -- 100 -- 100 -- D 113 (25.degree. C., 5 cm/min, cm) Thin film oven test 47 -- 42 -- 40 -- D 1745 (Pen. of residue % of original Pen.) Solubility in Tri- 99.0 -- 99.0 -- 99.0 -- D 2042 chloroethylene (wt %) __________________________________________________________________________